Fire blight can attack red tip photinia, but it is not as common as with pears and some other susceptible plants. Generally it attacks new growth in spring and doesn't tend to attack older growth or attack during the summer months. 
Bottom line is that is COULD be fire blight but I'd check the brown branches following them down to where they connect to living tissues. Look for girdling, freeze cracks/split bark, borer holes, etc. Prune out the dead growth and if none of the above alternative causes are detected make pruning cuts about 6" below the dead area into living tissues and spray pruners with Lysol or dip into rubbing alcohol between cuts.
I also noticed a hackberry volunteer in the red tip shrub.